The present invention relates to processing omnidirectional image/video content, and more particularly, to a method and an apparatus for decoding a projection-based frame with a 360-degree content (e.g., 360-degree image content or 360-degree video content) represented by triangular projection faces packed in an octahedron projection (OHP) layout.
Virtual reality (VR) with head-mounted displays (HMDs) is associated with a variety of applications. The ability to show wide field of view content to a user can be used to provide immersive visual experiences. A real-world environment has to be captured in all directions resulting in an omnidirectional image/video content corresponding to a viewing sphere. With advances in camera rigs and HMDs, the delivery of VR content may soon become the bottleneck due to the high bitrate required for representing such a 360-degree image/video content. When the resolution of the omnidirectional video is 4K or higher, data compression/encoding is critical to bitrate reduction.
In general, the omnidirectional video content corresponding to the viewing sphere is transformed into a sequence of images, each of which is a projection-based frame with a 360-degree image/video content represented by projection faces arranged in a 360-degree Virtual Reality (360 VR) projection layout, and then the sequence of the projection-based frames is encoded into a bitstream for transmission. However, if the employed 360 VR projection layout is not properly designed, it is possible that the projection-based frame is not compact and/or has many image content discontinuity boundaries that are caused by packing of the projection faces.